Plastic-worked member and production method thereof

Abstract

A metal ingot ( 1 ) solidified through unidirectional forced-cooling from a cooling member ( 100 ) to an end surface of a stopper ( 13 ), by the cooling member, of molten metal ( 1′ ) teeming via a molten metal inlet ( 101 ) of a closable mold ( 12 ) into a mold cavity ( 16 ) is plastic-worked at percent working equl to or higher than a predetermined level to obtain a plastic-worked member. The end surface of the stopper and the cooling member partially define the mold cavity. The plastic-worked member is improved in mechanical characteristics that have heretofore been inferior on the side of the end surface of the stopper and is increased in entire strength.

1 . A plastic-worked member obtained using a closable mold by plastic working, at percent working equal to or higher than a predetermined level, of a cast ingot produced through unidirectional forced-cooling of molten metal teeming via a molten metal inlet, wherein the forced-cooling is performed by means of a cooling member, an end surface of a stopper for stopping up the molten metal inlet serves as a portion of the inner surface of the mold, and the cooling member serves as another portion of the inner surface of the mold.  
     
     
         2 . A plastic-worked member according to  claim 1 , wherein the unidirectional forced-cooling is attained from a side of the cooling member to a side of the end surface of the stopper.  
     
     
         3 . A plastic-worked member according to  claim 1 , wherein the percent working is attained through single-step plastic working.  
     
     
         4 . A plastic-worked member according to  claim 1 , wherein the percent working is attained through multi-step plastic working.  
     
     
         5 . A plastic-worked member according to any one of claims  1 ,  3  and  4 , wherein the predetermined level is 25%.  
     
     
         6 . A plastic-worked member according to any one of claims  1 ,  3  and  4 , wherein the predetermined level is 50%.  
     
     
         7 . A plastic-worked member according to any one of claims  1  and  3  through  5 , wherein the plastic working is partial plastic working performed on the cast ingot.  
     
     
         8 . A plastic-worked member according to any one of claims  1  and  3  through  6 , wherein the plastic working is performed on at least a portion of the cast ingot including a portion on a side of the end surface of the stopper.  
     
     
         9 . A plastic-worked member according to  claim 1 , which serves as an intermediate product.  
     
     
         10 . A plastic-worked member according to  claim 1 , which serves as a final processed product.  
     
     
         11 . A plastic-worked member according to any one of claims  1 ,  7  and  8 , wherein the plastic working is any one of cold forging, hot forging, forging-elongation, rolling, extrusion, component rolling and rotary forging.  
     
     
         12 . A plastic-worked member according to  claim 1 , wherein the metal is aluminum or aluminum alloy.  
     
     
         13 . A plastic-worked member according to  claim 1 , wherein DAS of a metallographic structure as observed on a side of the end surface of the stopper is 1.1 to  10  times that on a side of the cooling member.  
     
     
         14 . A plastic-worked member according to  claim 1 , wherein a grain size in terms of metallographic structure as observed on a side of the end surface of the stopper is 1.05 to 7 times that on a side of the cooling member.  
     
     
         15 . A plastic-worked member according to  claim 1 , wherein, in relation to a size of grains that form a secondary phase of a plastic-worked member crystal, the grain size as observed on a side of the end surface of the stopper is at least 1.2 times that observed on a side of the cooling member.  
     
     
         16 . A production method of a plastic-worked member comprising the steps of using a closable mold that has a molten metal inlet and a mold cavity that is partially defined by an end surface of a stopper and by a cooling member; unidirectionally forced-cooling molten metal teeming via the molten metal inlet into the mold cavity to solidify the molten metal into a cast ingot; and plastic-working the cast ingot at percent working of at least a predetermined level.  
     
     
         17 . A production method of a plastic-worked member according to  claim 16 , wherein the step of unidirectionally forced-cooling the molten metal is attained from a side of the cooling member to a side of the end surface of the stopper.  
     
     
         18 . A production method of a plastic-worked member according to  claim 16 , wherein the percent working is attained through single-step plastic working.  
     
     
         19 . A production method of plastic-worked member according to  claim 16 , wherein the percent working is attained through multi-step plastic working.  
     
     
         20 . A production method of a plastic-worked member according to any one of claims  16 ,  18  and  19 , wherein the predetermined level is 25%.  
     
     
         21 . A production method of a plastic-worked member according to any one of claims  16 ,  18  and  19 , wherein the predetermined level is 50%.  
     
     
         22 . A production method of a plastic-worked member according to any one of claims  16  and  18  to  20 , wherein the plastic working is partial plastic working performed on the cast ingot.  
     
     
         23 . A production method of a plastic-worked member according to any one of claims  16  and  18  through  21 , wherein the plastic working is performed on at least a portion of the cast ingot including a portion on a side of the end surface of the stopper.  
     
     
         24 . A production method of a plastic-worked member according to any one of claims  16 ,  22  and  23 , wherein the plastic working is any one of cold forging, hot forging, forging-elongation, rolling, extrusion, component rolling, and rotary forging.